Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This means that the car's computer has detected a problem with the heater that helps keep a special fluid warm. This fluid is used to make the car's exhaust cleaner. It's like when a heater in your house isn't working properly.
The P20C3 code indicates that the control circuit for the third reductant heater is reading a low voltage, which suggests a problem with the heater's operation.
The reductant heater is part of the Selective Catalytic Reduction (SCR) system, which reduces nitrogen oxide emissions in diesel engines. Heater C is responsible for maintaining the temperature of the Diesel Exhaust Fluid (DEF) to prevent it from freezing. A low circuit reading suggests issues such as a faulty heater, poor wiring, or a malfunctioning control module.
• Check Engine Light is on
• Possible reduction in fuel efficiency
• Increased exhaust emissions
• Faulty reductant heater
• Damaged wiring or connectors
• Defective control module
Reductant: A substance used to reduce emissions, typically Diesel Exhaust Fluid (DEF).
SCR: Selective Catalytic Reduction, a system that reduces nitrogen oxide emissions in diesel engines.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage.
• Test the reductant heater for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the faulty reductant heater.
• Reprogram or replace the control module if necessary.
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $500
Moderate
• Ford F-Series
• Chevrolet Silverado
• Ram 2500
• Regularly inspect and maintain the DEF system.
• Ensure quality DEF is used.
• Keep the vehicle's electrical system in good condition.
Sensor Issue
• Have the vehicle inspected by a professional.
• Avoid ignoring the Check Engine Light.
• Regularly maintain the DEF system.
Check with the vehicle manufacturer for specific warranty coverage on emissions-related components.
This code has become more common with the increased use of SCR systems in diesel engines to meet stricter emission standards.
Moderate – While it may not immediately affect drivability, it can lead to increased emissions and potential future issues.
Driving with a malfunctioning emissions system may not comply with local emissions regulations.
• Engine at operating temperature
• DEF system active
The reductant heater is typically located near the DEF tank or along the DEF line.
Q: What is a reductant heater?
A: A reductant heater keeps the DEF fluid from freezing, ensuring it can flow properly.
Q: Can I drive with a P20C3 code?
A: While the car may still drive, it's best to fix the issue to avoid increased emissions and potential future problems.
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